无水电化学法制备铜锌锡硫薄膜的研究

Nowadays, the high cost problem becomes a bottleneck of the photovoltaic applications. CZTS thin film solar cell, which is fabricated by inexpensive electrochemical deposition(ED) is regarded as one of the most promising solutions. However, CZTS solar cell prepared by conventional ED with aqueous solution has obtained limited effeciency, which is probably due to the hydrogen evolution at the working eletrode and low quality of layers as many other non-vaccum methods. To solve this problem, a new approach called "electrochemical co-deposition with non-aqueous solvent" is utilized in this project.Copper, zinc and tin is co-deposited onto the substrate with ionic liquid electrolyte,that provides a wide window of electrochemical potential. In the ED process, the pulse parameters will be controlled and optimized to well modify the layer morphology. Together with the assistance of ultrasonic condition, a dense and smooth Cu-Zn-Sn precursor with good adhesion will be obtained.It is followed by annealed in sulfur contained atmosphere to achieve a high quality single phase polycrystalline CZTS film as the absorber of PV device. This project provides a new idea and approach to the low cost thin film photovoltaics.

当今影响太阳电池普及应用的主要瓶颈在于成本，而采用电化学法沉积制备铜锌锡硫电池是一个非常有希望的低成本光伏解决方案。然而在常规的水相电沉积工艺中，受制于阴极析氢现象以及其它一些非真空成膜普遍面临的镀层质量问题，在此基础上制备的CZTS电池性能并不理想。针对这个问题，申请人拟采用一种"无水电化学共沉积"的方法，用离子液体代替去离子水作为电解质，利用其较宽的电化学窗口，选择合适的共沉积电位，将金属Cu、Zn、Sn一步沉积到阴极。在这个过程中，通过对电流脉冲的控制和参数优化，实现对镀层形貌的调控，结合超声波等物理辅助条件的引入，获取致密、平整且附着良好的Cu-Zn-Sn预制层。随后，预制层再经过高温硫气氛中的退火，得到物相纯净的高质量CZTS多晶薄膜，为制备高效率CZTS电池打下基础。该项目的开展，将为低成本薄膜光伏技术提供新的思路和方法。

目前，高发电成本是影响太阳能发电推广应用的最大障碍。发展一种环境友好的、低成本高丰度太阳电池材料，结合绿色低能耗的制备工艺，有希望将发电成本降低到可以接受的水平。针对这个目标，本项目开发出了一种基于离子液体电化学沉积铜锌锡硫薄膜的方法。通过对关键工艺参数的摸索，获得了在金属电极表面沉积致密平整、精确配比的铜锌锡合金预制层的制备工艺；结合XRD、EDX、SEM、XPS、Raman等测试手段的综合分析，掌握了CZT预制层在含S、Se气氛下退火的相变规律。最终制备出转换效率为3.87%的CZTS太阳电池器件，这是国际上首次采用离子液体电沉积制备出的有效率的CZTS太阳电池。项目成果展示了一种新型的绿色、低成本液相合成技术，并且用于制备高丰度、环保型光伏材料及器件，是绿色化学技术在能源领域应用的成功示范，为发展低成本光伏技术提供了新的思路。